Trifluoromethyl/metal compounds have found limited use in the prior art as intermediates for the preparation of certain biological or pharmaceutical reagents.
However, the prior art discloses that trifluoromethyl-substituted organometallic compounds, where the metal is electropositive, are difficult to form. According to the literature, because of the strong electronegative fluorine atoms, a positive charge is induced on the trifluoromethyl carbon atoms. Stability of any bond formed between an electropositive element and such carbon atom is adversely affected. As such, in the typical reaction to form these trifluoromethyl-substituted metal compounds, the compound resulting is principally derived from a difluoromethyl carbon elimination and rearrangement, the end result being to produce a metal fluoride. For example, for trifluoromethylboron compounds, the positive charge on boron may be removed either by coordination of a fourth ligand or by (.pi.--.pi.) bonds. As such, it is not surprising to find that the majority of known trifluoromethylboron compounds are derived from the tetravalent boron e.g. CF.sub.3 BF.sub.3.sup.- ; (CF.sub.3).sub.2 BF.sub.2.sup.- ; CF.sub.3 BF.sub.2.N(CH.sub.3).sub.3 and the like.
Recently, a process has been developed where trivalent boron compounds have been manufactured by using a phosphorus salt combined with the CF.sub.3 containing halide e.g. P[N(C.sub.2 H.sub.5)].sub.3 and a CF.sub.3 bromide. The non-isolable intermediate [(C.sub.2 H.sub.5).sub.2 N].sub.3 PBr.sup.+ CF.sub.3 .sup.- is believed to be the active trifluoromethyl transfer agent for the reaction. See for example Barger, et al, Journal of Fluorine Chemistry 31 89-92 (1989). While the desired product (trifluoromethyl amino borane) was identified, yields of product were severely depressed (25%).
The phosphorus route for producing trifluoromethylmetal compounds has also been applied to the preparation of silicon compounds. See, Ruppert, et al Tetrahedron Letters 25 2195 (1984). For example, starting with trimethyl silicon chloride 90% yields of trifluoromethyl(trimethyl)silane are obtained. Similar success has been obtained by using aminosilanes where both bis and tris trifluoromethyl compounds have been isolated. See Chemical Abstracts Selects; Organofluorine Chemistry, 111 9, no. 115-298 f.
Accordingly, there is a need to more fully develop the chemistry of the haloalkylation process and prepare and study the ease of preparation and reactivity of the haloalkylated metal compounds.